Nuclear leakage detection system using wire or optical fiber

ABSTRACT

A system for detecting and containing a breach in a container includes a first containment layer and a first sensor layer. The first sensor layer includes at least one signal path extending the first sensor layer. The first sensor layer may be provided by either a fiber optic or a wire. An inability of the at least one signal path to conduct a signal from a first end to a second end represents either a breach, or an attempted breach, from outside the container or a failure of the container. The containment layers may seal against any leakage of material in a container subsequent to a breach either from within or from without. An additional layer may be provided to protect against intrusion and may be made from material such as Kevlar. The detection and containment system may be implemented to protect tunnels, pipelines, hatches and manhole covers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/779,124 filed May 13, 2010 entitled “Nuclear Leakage Detection SystemUsing Wire Or Optical Fiber” which issued as U.S. Pat. No. 7,924,166 onApr. 12, 2011.

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application No. 61/179,143, filed on May 18, 2009.

This application is related to: U.S. Pat. No. 6,995,353 issued on Feb.7, 2006, entitled TAMPER-PROOF CONTAINER; U.S. Pat. No. 7,608,812,issued Oct. 27, 2009, entitled TAMPER DETECTION SYSTEM; U.S. Pat. No.7,211,783 issued May 1, 2007, entitled TAMPER-PROOF CONTAINER; U.S. Pat.No. 7,098,444 issued Aug. 29, 2006, entitled TAMPER PROOF CONTAINER;U.S. Pat. No. 7,332,728, issued Feb. 19, 2008, entitled TAMPER PROOFCONTAINER; U.S. Pat. No. 7,394,060 issued Jul. 1, 2008, entitled TAMPERDETECTION SYSTEM HAVING A PLURALITY OF INFLATABLE LINER PANELS WITHOPTICAL COUPLERS; U.S. Pat. No. 7,482,924 issued Jan. 27, 2009, entitledCARGO CONTAINER SECURITY SYSTEM COMMUNICATIONS, U.S. Pat. No. 7,619,226,issued Nov. 17, 2009, entitled INTEGRATED OPTICAL NEUTRON DETECTOR, andU.S. patent application Ser. No. 12/283,302, filed Sep. 9, 2008 entitledPIPELINE SECURITY SYSTEM.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

BACKGROUND OF THE INVENTION

The nuclear power industry has, almost from its very beginning, had todeal with the issue of disposing of the nuclear waste generated by itsprocesses. Some may consider that the nuclear industry, having grown inan erratic manner, has been unable to deal with this issue in a way thathas resolved the many issues that come with it.

If a solution to the problem of nuclear waste disposal is not found, theconsequences to the environment and the health and safety of largepopulations of people, along with the economic impact, are immeasurablylarge.

The problem, of course, is that there is, to date, no acceptable methodof “permanent” disposal of nuclear waste. It is up for debate what“permanent” can ever mean, when the half-life of radioactive waste is inthe thousands and millions of years. The current solution, and onelikely for the foreseeable future, is “out of sight—out of mind.”Removing spent nuclear fuel from reactors of any sort, whether fromcommercial power plants, university labs or military installations, anddisposing of the spent fuel is difficult, dangerous and expensive.Nuclear waste, especially intermediate and high-level waste, can be heldon site for decades while low-level waste may be quickly transported topermanent storage or burial sites. “Nuclear waste” can also include manycollateral items used in nuclear installations such as: clothing,instruments, equipment and associated chemicals.

The current state of affairs in the nuclear industry, with respect tonuclear waste, is best summarized in the collective writings ofenvironmentalist Lorna Salzman, who says that “the longer the problemremains unsolved, the less credible are assurances that an acceptablesolution will eventually be found.”

In order to minimize the difficulties of finding a “permanent” solution,while constantly storing and moving millions of drums and containers ofall sorts of radioactive waste of varying degrees of emission intensity,it is indispensable that the drums and containers be made as secure fromthe loss of material containment as possible. Notwithstanding continuousimprovement over the years since the nuclear industry began drums andcontainers remain vulnerable to leakage of radioactive materials for awide variety of technical and operational reasons, such as, corrosion,accident, vandalism and sabotage.

There is a need, therefore, to be able to continuously monitor each drumor container against corrosive leakage, accidental damage, theft or actsof terrorism. Further, these security systems need to be able to reportupon the detection of any type of change in status in a manner that istimely and effective.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, a detection and containment system for detecting andcontaining a breach in a container includes a first containment layer; afirst sensor layer coupled to the first containment layer and having atleast one signal path extending across substantially an entire area ofthe first sensor layer; and a second containment layer coupled to thefirst sensor layer such that the first sensor layer is sandwichedbetween the first and second containment layers. A failure of the atleast one signal path to conduct a signal from a first end to a secondend signifies a breach, or an attempted breach, of at least one of thefirst and second containment layers.

Embodiments of the present invention are particularly useful to monitor,in real-time, the storage of hazardous material, such as nuclear wastedrums holding radioactive material, to ensure there is no leakage thatmight pollute a facility or the environment. The system constitutes afirst line of defense to detect, for example, any attempts to break intoa storage drum of radioactive nuclear waste.

Further, embodiments of the present invention are applicable to accessdoors or hatches leading to protected spaces. In one non-limitingexample, the detection and containment system is associated with ahatch, which could include a manhole cover or door. Any attempts tobreach the hatch or door will then be detected by the present system.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Various aspects of at least one embodiment of the present invention arediscussed below with reference to the accompanying figures. It will beappreciated that for simplicity and clarity of illustration, elementsshown in the drawings have not necessarily been drawn accurately or toscale. For example, the dimensions of some of the elements may beexaggerated relative to other elements for clarity or several physicalcomponents may be included in one functional block or element. Further,where considered appropriate, reference numerals may be repeated amongthe drawings to indicate corresponding or analogous elements. Forpurposes of clarity, not every component may be labeled in everydrawing. The figures are provided for the purposes of illustration andexplanation and are not intended as a definition of the limits of theinvention. In the figures:

FIG. 1 is a diagrammatic view of a sheet containing an optical orelectrical path therein, in accordance with an embodiment of the presentinvention;

FIG. 2 is a diagrammatic view of a section of a container having aplurality of sensor sheets wrapped along contiguous sections of thecontainer;

FIG. 3 is a block diagram of an embodiment of the present inventionhaving a plurality of interconnected sensor sheets;

FIG. 4 is a block diagram of an embodiment of the present invention inwhich each of the sensor sheets has its own signal source and detectorand/or power supply and associated circuitry;

FIG. 5 is an exploded view of a sensor assembly in accordance with anembodiment of the present invention;

FIG. 6 is an exploded view of a sensor assembly in accordance withanother embodiment of the present invention;

FIG. 7 is a layer of a sensor assembly comprising path cutting material;

FIGS. 8A and 8B are perspective and side-views of an embodiment asapplied to a planar rectangular item such as a door; and

FIGS. 9A and 9B are perspective and side-views of an embodiment asapplied to a planar, but circular, item such as a manhole cover.

DETAILED DESCRIPTION OF THE INVENTION

The disclosures of U.S. Pat. Nos. 6,995,353, 7,211,783, 7,098,444,7,332,728, 7,394,060, 7,482,924, 7,619,226 and 7,608,812, U.S. patentapplication Ser. No. 12/283,302, U.S. Provisional Patent Application No.61/179,143 and U.S. patent application Ser. No. 12/779,124 areincorporated by reference herein for all purposes.

Embodiments of the present invention provide an effective fail-safeleakage detection system that encapsulates the outside walls of any sizeor configuration of container and which secures the volumetric space ofthe container with a signal path carried by an optical fiber orelectrical wire disposed in the system, as will be described below. Anyintrusion, or attempted intrusion, whether accidental or deliberate,that breaches, or comes close to breaching, the container wall will beinstantaneously detected. The primary mode of detection is that ofdetecting a loss of a signal in the signal path due to a mechanicalbreak, e.g., a cut, in either the optical fiber or the electrical wire.In the case of the optical fiber, a radiation leak is detected by thereduction in the signal due to the effects of the radiation on theoptical fiber. Further, either a leak from within, or intrusion fromoutside, will result in an immediate local and/or remote alarm via acommunication link coupled to the optical fiber or electrical wire.

The invention is also useful to monitor, in real-time, the storage ofhazardous material, such as nuclear waste drums holding radioactivematerial, to ensure there is no leakage that might pollute a facility orthe environment. In one embodiment, the leakage of radioactive material,whether by an attempt to breach or due to a failure of the container,will be detected by the radiation's effect on the optical fiber. Thus,the system constitutes a first line of defense to detect, a storage drumfailure or any attempts to break into a storage drum of radioactivenuclear waste.

A flexible and wrappable sensor sheet is provided having an opticalfiber or electrical wire disposed therein in a zigzag, symmetrical orother pattern that covers substantially the entire area of the sheet. Alight or current signal source is provided at one end of the continuouscircuit to introduce light or current signal into the path. A light orcurrent detector is coupled to the other end of the path to sense thecontinuous or pulsed light signal or electrical signal transmittedthrough the path on a fail-safe basis. The loss of a detectable signalmay be due to a cut in the signal path or damage to an optical fiberpath due to radiation. Additionally, the loss of the signal may be dueto an equipment failure, for example, failure of the signal source, apower supply, a detector and the like. Regardless of the reason for theloss of the signal, therefore, an alarm will be asserted. The detectionsignal may be encrypted or actively interrogated by a monitoring stationto prevent theft, sabotage, or acts of terrorism. Additionally, anyattempts to cloak, block, jam or otherwise interfere with the signalwill be detected by operation of the regular interrogation and/orencrypted signal.

Alternatively, each sensor sheet section can have its own light orcurrent source and its own respective light or current detector forsensing the presence or absence of a signal from the respective paths tomore specifically locate the part of the drum or container where theleakage or intrusion has taken place.

A sensor sheet or layer in accordance with an embodiment of the presentinvention is illustrated diagrammatically in FIG. 1. A sheet 10 offlexible and wrappable material has disposed therein, and acrosssubstantially the entire area thereof, an optical fiber or electricalwire 12 having a first end and a second end. The optical fiber orelectrical wire 12 defines a continuous signal path from the first endto the second end.

A light source, in the case of an optical fiber, or an electrical signalsource, in the case of an electrical wire, provides a light orelectrical signal, respectively, to the first, i.e., input end of thepath. A light detector, in the case of an optical fiber, or anelectrical signal detector, in the case of an electrical wire, iscoupled to the second or receiving end of the signal path and detectsthe light or electrical signal from the path and provides an outputsignal indication thereof.

The optical fiber or electrical wire can be woven into a fabric sheet orcan be disposed in a sheet of non-woven material. The sheet can be ofany material that is flexible and wrappable such that the sheet can bewrapped around the outer surface of a container or other structure to beprotected.

The sheet can contain, or have added to it, a resin or other materialthat can be hardened or rigidized after the container is wrapped withthe sensor sheet to act as a protective covering and to retain the sheetabout the outer surface of the container. The sheet may be retainedabout the container by other means as well, such as an outer protectivecovering placed over the sheet wrapped onto the container and which issecured to retain the sensor sheet in place on the outer surface of thecontainer. The sensor sheet may be sandwiched or laminated with othermaterials providing intended protection or other functionality, such asstructural protection, abrasion resistance, and the like, as will bedescribed below.

In one embodiment, the sensor sheet is made of a flexible rollablematerial. The sheet is rolled up prior to installation on the containeror other elongated object to be protected. The sheet is unrolled duringinstallation and wrapped around the container or section thereof toprovide a sensor that covers the entire intended area of the containersurface.

The individual sensor sheets can be interconnected to provide onecontinuous optical or electrical path through the adjacent sensorsections. Alternatively, each sensor section can have its ownindependent light or current source, its own light or current detectorand its own independent power supply or alarm transmission system.

In one embodiment, the optical fiber can be woven into the fabric as itis made such that a long web of fabric can be manufactured and rolledonto a reel for shipment to an installation site. The fabric can beunrolled and extended along a section of container and secured theretoto substantially cover the outer surface of the container section.Similar fabric webs can be wrapped about adjacent sections of thecontainer such that the entire length of the container, or an intendedextent of the container, is covered by the sensor fabric. Opticalconnectors or couplers are provided at respective ends of the websections and are interconnected to provide a continuous optical paththrough the adjacent web sections that cover the container. This methodallows a resolution to detect even a small breach of the container.

Light from a suitable source is introduced into one end of the sensorsheet or web and an optical sensor or detector is disposed at the otherend of the sensor sheet or web to detect light emanating from thecontinuous optical path. The light detector is coupled to signalprocessing circuitry that is operative to provide an alarm signal in theevent of failure to receive the detected light or the diminishment ofdetected light below a predetermined threshold.

A breach or break at any point in the optical path of the optical fiberwill cause a disconnection in the light signal, and the absence of lightat the light detector will trigger an alarm condition.

The optical fiber may be manufactured such that, if the fiber is exposedto radiation near the sensor sheet, either from within or outside of thecontainer, the optical transmissibility of the optical fiber is reduced,as discussed in U.S. Pat. No. 7,619,226. The optical fiber core and/orits cladding constitute a large size physical radiation detector thatintegrates the radiation over time and/or over the length and volumetricmass of the fiber, making the fiber sensitive to even low levelradiation. Local environmental background radiation can be measured tooffset the detection level designated to trigger an alarm.

The optical fiber is monitored for a change in its transmissibility, asindicated by reception of an attenuated light signal coming from itsoutput. An attenuated light signal that is below a predeterminedthreshold level can trigger an alarm. Thus, a signal may be received andstill indicate an alarm condition because of its lowered amplitude orother characteristic. The alarm can be in the form of an annunciatorand/or can be the sending of a message that can include informationabout the time or location of the breach.

Alternatively, a detected light signal that is below a predeterminedthreshold may be used to indicate that a visual and/or physical check ofthe system should be performed. For example, consider the case where theoptic fiber is configured to have reduced transmissibility in responseto being exposed to radiation. A detected signal that drops below thethreshold may indicate that there is radiation in the area and thisshould be investigated, if possible.

Any size container can be wrapped with a liner made of fabric or otherflexible material that can be wrapped over the outer surface of thecontainer. Any suitable material such as polymer resins can be employedthat can structurally and functionally hold optical fiber or electricalwire placed in any geometrical pattern, with any space resolutionbetween optical fibers or electrical wires. Each optical fiber orelectrical wire forms a single continuous optical or electrical pathway.Two or more sensor sheets may be employed to cover respective sectionsof a container, especially large containers where a single sensor sheetwould be impractical. A container divided into sections A, B, C and D isshown in FIG. 2. Each individual section can have its own light orcurrent source, or its own light or current detector. Each section canhave its own GPS/communication unit or location memory chip/communicatorso that any break in a section causes transmission of a detailedgeographical and time of intrusion signal to one or more containermonitoring stations.

The sensor sheets A, B, C or D, can be any length or width so as to fita container with appropriate coverage and length so that a break orintrusion into the container can instantly cause an alarm signalspecifying the exact position on the container, and, because of thegeometric resolution structure, the approximate size of the intrusion. Ahard resin can fix the sections securely to the container, and provideresistance to an intrusion or break and provide information in real-timeon the intrusion.

An embodiment of the present invention in which the sensor sheets areinterconnected to provide a single continuous signal path is shown inFIG. 3. The optical fiber or electrical wire providing the signal pathin each of the sensor sheets is serially interconnected with the opticalfiber or wire of adjacent sheets such that a single signal path isprovided from one end of the interconnected sheets to the opposite endof the interconnected sheets covering the entire container.

A signal source 10 provides an optical or electrical signal to thecontinuous path, depending on whether an optical fiber or electricalwire is used for the path. A detector 12 is coupled to the opposite endof the continuous path to sense the optical or electrical signal fromthe path and to provide an output signal to a processor 14 that isoperative to provide an alarm notification signal in the event of theloss of a signal from the signal path or in the event of a sufficientdegradation in the signal to cause an alarm condition.

An embodiment in which each of the sensor sheets has its own signalsource and detector is shown in FIG. 4 in schematic form. In thisembodiment, each of the sensor sheets A, B, C and D has a signal source20 a-20 d coupled to one end of the signal path of the respectivesheets. The other end of the signal path of the respective sheets iscoupled to respective detectors 22 a-22 d. The output from each of thedetectors 22 a-22 d is connected to a processor 24 that provides anoutput signal in the event of an alarm condition sensed by any one ormore of the detectors. The alarm notification in this embodiment canprovide an indication of which detector has sensed an alarm conditionand therefore indicate in real time which sensor sheet and, therefore,which section of the container, has experienced an actual or attemptedintrusion.

As shown in FIG. 4, various combinations of power supplies may beprovided for the signal sources and detectors. For example, a singlepower supply 26 a may be provided to power a signal source 20 a and adetector 22 a for a specific sheet A. Alternately, a signal source 20may have its own power supply 26 b and the corresponding detector 22 bmay have its own power supply 26 c. The processor 24 may have its ownpower supply 26 d. One of ordinary skill in the art will understand thatthe provisioning of power supplies for the signal sources, detectors andthe processor is a design choice driven by reliability and redundancyrequirements the overall system may have to meet.

In one embodiment of the present invention, the sensor sheet containingthe fiber or wire is fashioned in a sandwich manner between layers ofprotective resin. The resin may be embedded with self-sealing chemicalmaterials, known to those skilled in the art, having specifications tocause a delay in the leakage of material from within the container dueto either corrosive or accident-induced, or deliberate, intrusion fromoutside the container.

As described above, when either the optical fiber or electrical wireembedded in the sensor fabric is corroded, drilled, pierced or cut, theoptical or electrical circuit pathway is broken and the light orelectrical detector will fail to detect the continuous transmission ofeither the light or electrical signal, and the detector will transmit analarm signal. The optical or electrical signal is transmittedcontinuously and hence functions as a fail-safe signal that will createan alarm for any reason that the circuit pathway is broken, or when thesignal is no longer being received, including loss of power or componentfailure. In some instances, as described above, a signal may still comethrough but if its intensity or amplitude is less than somepredetermined threshold, then an alarm will be sounded.

Advantageously, a single optical or electrical circuit encapsulates theentire volumetric space of the container when the sensor sheet iswrapped around the outer surface of a hazardous material storagecontainer. A container may be a drum or any other volumetric structure.

The sensor sheet sandwiched between single or multiple layers of resin,or additionally other types of fabric with self-sealing or protectivecharacteristics, can be made as a single wrap-around sheet for theoutside of a cylindrically shaped nuclear waste drum or may be made insections that are optically or electrically interconnected by the use ofconnectors, as described above. Sections may be made for the bottom andtop of a drum with the wrap-around side, top and bottom allinter-connected with one another to provide a single or multiple circuitdetector system.

When the container is breached, from within or from without, the systemwill generate an alarm signal. Almost simultaneously, the resin and/orfabric outer layers will act to provide a seal by, for example, achemical reaction from coming into contact with air, or by other means,and delay the flow of material from within the drum to the outside ofthe drum.

The sandwich construction sets the optical fiber or electrical wiresensor sheet between two, or multiple, layers of special resins orself-sealing polymers. Further, fabrics or materials with specialproperties, such as Kevlar®, can be used to protect two dimensional,i.e., flat surfaces, such as high security doors or walls. Thus,embodiments of the present invention provide a detection system forlow-level leakage as might be caused by a gunshot or an explosivedevice. Detecting the presence and location of damage caused by a bulletor explosive penetration makes the Kevlar protection more effective. Thefunctional benefit of such “protection” applications is to “detect anddelay.”

Conventional security doors, such as ones made of manganese steel orreinforced walls, might delay an intruder but security responders mayonly be alerted, or become aware, after an intruder has already entered,and possibly left, a secured area. As a result, the intruder may gainextra time to escape because the time of response can be calculated orpredetermined by observation. If the detection is made immediately uponan attempted entry, however, the extra time needed to gain entry throughthe protection layers can be used to increase the probability ofcapturing the intruder, instituting alternate security procedures, oralternately sounding an alarm warning the intruder off. This incipientalarm feature can provide vital time in giving responders sufficienttime to take action.

In one embodiment of a sandwich-type sensor sheet, a 3-ply constructionsensor assembly 502 is provided as shown in FIG. 5. Here, the layers areshown spaced apart for ease of explanation, but one of ordinary skill inthe art would understand that they are intended to be adjacent to oneanother in application. The sensor assembly 502 includes an inneradhesive, self-sealing layer 504-1, a sensor layer 506 that includes anoptical fiber and/or an electrical wire and an outer adhesive, and aself-sealing layer 504-2 positioned on the other side of the sensorlayer or 506. The 3-ply construction sensor assembly 502 is attached toa surface 510 of a container and then covered with a protective coatingor layer 512 that provides mechanical protection of the sensor assembly502. The inner and outer self-sealing layers 504-1, 504-2, may comprisea resin material.

In the configuration shown in FIG. 5, as soon as either the outer(intrusion) layer 504-2 or inner (leakage) layer 504-1 is pierced, thesensor layer 506 in the center is also pierced causing a detectionsignal. In turn, an alarm signal is immediately transmitted to adesignated communications link to pass to an authorized monitoringstation.

In another embodiment of a sandwich-type sensor sheet, a 5-plyconstruction sensor 602 is provided as shown in FIG. 6. Here, the layersare spaced apart for ease of explanation as well. The sensor assembly602 includes an inner (leakage) adhesive, self-sealing layer 504-1followed by an inner protective layer 604-1 which may be made from, forexample, Kevlar® material, then located next to a sensor layer 506. Anouter (intrusion) protective layer 604-2, also made of Kevlar®, ispositioned on the other side of the sensor layer 506 and is followed byanother adhesive, self-sealing layer 504-2, that is, an outer(intrusion) layer. The 5-ply construction sensor 602 is then provided onthe outer surface 510 of the container and then covered with aprotective coating layer 512, as described above.

Advantageously, in an example based on one embodiment of the presentinvention, if the outer layer 504-2 is breached, the detection signal istriggered and the inner layer 504-1 provides an effective delay time sothat the breach can be dealt with by responders in a timely manner. Inaddition, the self-sealing feature of the layer prevents or delays thepassage of material from within the container into the storage facilityor outside environment.

Additionally, another feature of the present invention provides that thesingle or multiple layers of resin contain micro bubbles of chemicalcompounds that, when contacted with the material effusing from thebreach or in contact with air, will coat the effusing material with acolor dye to more readily facilitate visual location of where on thecontainer or drum walls the leakage is occurring. The actual time delayduration of the “detect and delay” sequence can be chosen for a specificapplication requirement by selection of specific resin compounds,chemical compounds, or fabric as known by those skilled in the art.

Embodiments of the present invention thus offer a unique “detect anddelay” feature for leakage of a volumetric container by operation oflayering of sensor sheets, resins, and fabrics in differentconfigurations with specifications suitable to protecting virtually anytype of vital infrastructure such as: nuclear, chemical or biologicalmaterial whether as waste or newly manufactured material. Additionally,this construction is amenable to being employed as a wrappable “detectand containment sleeve” around critical infrastructure pipes, such asfound in hi-pressure steam generating systems of nuclear power plants,where incipient fissures might be particularly hard to detect bymonitoring pressure gauges ahead of a catastrophic rupture.

In addition, a resilient or gel-like material may be used as theself-sealing layer in order to prevent leaks due to, for example, abullet or other projectile passing through the layers. The resiliencymay be provided by materials such as rubber or plastic similar to thosematerial used in, for example, self-sealing gasoline tanks.

One of ordinary skill in the art will understand that either of theembodiments described above may have multiple sensor layers in order topossibly identify a “direction” of incursion by determining which layerwas first breached. In addition, if optical fiber that responds toradiation were to be used in a multiple sensor layer application, anychange in transmissibility as between the two layers might be indicativeof whether the radiation is coming from inside the container or fromoutside and, therefore, determine what type of response should be made.Further, the sensor layer may be provided in either of the protection orthe self-sealing layers.

In another embodiment of the present invention, in order to increase thefeature of delay in the dual strategy of the “detect and delay”protection system, shards of plastic, metal, or other materials that aredesigned to snare and delay a drill bit are mixed into a layer of resin700 as shown in FIG. 7. Thus, when an ensnared shard 702 is caught on adrill bit it acts as a scythe to cut the optical fiber or electricalwire 12 embedded or affixed to the sensor sheet thereby triggering thedetection signal. Further, the sensor layer 506 may have shards 702disposed therein to also cut the path if hit by a drill. One wouldunderstand that any movement of a shard 702, whether by drill, bullet orshock blast, could cause the shard to cut the path 12.

Further, one or more of the signal source 20, the detector 22 and thepower supply 26 may be encapsulated, i.e., “potted,” and placed in anyone of the self sealing layers 504, the protective layers 604 or thesensor layer 506. In this manner, either of the sandwich-type sensorsheets 502, 602 are “integrated” systems. These devices need not beplaced in the same layer and could be “distributed” in different areasof the sensor sheets, i.e., not aligned with one another, so that theyare not susceptible to being damaged by the same intrusion, for example,a single projectile that damages all three devices. Of course, one wouldunderstand that the signal source 20, the detector 22 and the powersupply 26 may need to be either placed in a location that is verydifficult to be reached by an intruder or in an area with additionalprotection. This additional protection may not be necessary, however, asthe system is intended to be a fail-safe system where the processor 24is configured to trigger an alarm condition if a signal is no longerreceived from the detector 22.

The optical fiber can be chosen or configured such that it exhibitsreduced optical transmissibility when exposed to a corrosive agent such,for example, an acid. This reduction in optical transmissibility may bedue to the corrosive agent contacting a part of the optical fiber suchas, but not limited to, the sheath, the cladding, a coupling or the corewhere one or more of them has been modified to react or breakdown whencoming into contact with the corrosive agent. Additionally, thecorrosive agent may be in a solid, liquid or gaseous form and stillaffect the optical transmissibility. The corrosive agent may be in thecontainer being protected by the sensor sheet of the present inventionand its release may be due to a breach or failure of the container.Alternatively, the corrosive agent may have been applied to thecontainer and, therefore, to the present system, in an attempt to eithergain access thereto or cause the contents, which might or might not becorrosive themselves, to be released into the environment.

The optical fiber can be chosen or configured such that it exhibitsreduced optical transmissibility when exposed to chemically activematerials or compounds, such as, for example, Nitrogen, as might befound in fertilizer or explosives. This reduction in opticaltransmissibility may be due to the chemically active material contactinga part of the optical fiber such as, but not limited to, the sheath, thecladding, a coupling or the core where one or more of them has beenmodified to react or breakdown when coming into contact. Additionally,the chemically active material may be in a solid, liquid or gaseous formand still affect the optical transmissibility. The material may be inthe container being protected by the sensor sheet of the presentinvention and its release may be due to a breach or failure of thecontainer. Alternatively, it may have been applied to the container and,therefore, to the present system, in an attempt to either gain accessthereto or cause the contents, which might or might not be chemicallyactive themselves, to be released into the environment.

Still further, the optical fiber may be chosen or configured such thatit exhibits reduced optical transmissibility when exposed to a pathogen,such as might be found in a biological hazard.

Embodiments of the present invention are not only applicable toprotecting a space, enclosure or container, as described above, but arealso applicable to protecting the access points to such protectedspaces. Thus, embodiments of the present invention may be applied toprotecting access hatches or hatch covers, including manholes andmanhole covers, for gaining entrance to, for example, ducts over sewersystems, water supplies, water valves or electrical conduits. Thesehatches may be in locations that are in low-trafficked areas and,therefore, mounting a sensing sheet in accordance with the teachingsherein provides for detection of hatch failure, unauthorized access orvandalism. The detection systems in accordance with the presentinvention may be applied either internally or externally to the hatch.This is especially advantageous in those hatch systems that implementmultiple hatches with a first, or exterior hatch, protecting or coveringa second, or interior, hatch. The detection systems of the presentinvention may be implemented in conjunction with, or in addition to,other known intrusion systems such as vibration sensors or systems thatrecord or detect the opening or accessing of a hatch.

Referring now to FIG. 8A, a generally rectangular hatch portion 800 hasa surface 802 and an edge 804 running around the surface 802. Thus, thehatch portion 800 has a thickness defined by the edge 804. A hatchportion 800 could be a door or other moving part of a hatch system thatcovers an opening. In accordance with an embodiment of the presentinvention, a security system 810 includes a combination of the sensor,containment and/or protection layers, as described above, and includesedge portions 812 to cover the corresponding edge 804 of the hatchportion 800. As a result, as shown in FIG. 8B, a side-view, the edgeportion 812 of the system 810 protects the edge 804.

Similarly, referring now to FIG. 9A, a generally circular manhole cover900 has a surface 902 and an edge 904 running around the surface 902.Thus, the manhole cover 900 has a thickness defined by the edge 904. Themanhole cover 900 could be removable or otherwise hinged as a door orother moving part of a hatch system that covers an opening. Inaccordance with an embodiment of the present invention, a securitysystem 910 includes a combination of the sensor, containment and/orprotection layers, as described above, and includes an edge portion 912to cover the corresponding edge 904 of the manhole cover 900 similar toa cap. As a result, as shown in FIG. 9B, a side-view, the edge portion912 of the system 910 protects the edge 904 of the manhole cover 900.

The edges of the system may be provided so as to wrap-around or underthe edges of the hatch or manhole cover to remove the opportunity forthe cover to be physically pried off. Further, any electronics, such asthe signal source and/or the signal detector could be placed on theunderside of the cover and protected by potting material.

The multilayer system of the present invention may be combined with asecurity hatch or door as described above. Thus, by attaching themultilayer system to, for example, a manganese or steel reinforced door,any attempts at breaching either the door or the area the door issecuring will be detected while, at the same time, the door performs itsfunction of protecting and/or delaying a possible breach.

Embodiments of the present invention are useful for protecting varioustypes of containers or enclosures for which security is deemed arequired feature. In addition to the nuclear storage containers notedabove, the invention is useful to protect safes, filing cabinets orother containers or enclosures where there is a security need forprotection of the container contents. The invention is useful to protectvending machines that dispense cash, credit and other sensitiveinformation, documentation, or goods of value, including ticketingmachines of all types, ATM machines, machines for dispensing railroad,airline, bus tickets and the like. A particular application is in theprotection of gambling machines, such as machines issuing lotterytickets, slot machines, electronic poker games or other games. Alsoprotectable according to the invention are computers and systems,devices and machines that dispense information or data or that areusable to gain entry into secure environments.

Among the applications in which the detection system of the invention isuseful are the following:

Air, sea and land cargo

Pipelines—factory or field applications

Cash, credit card and/or debit card handling machines, for example, ATMs

Remote railway and other ticketing machines

Buildings—enclose the space to detect and delay

Storage tanks and tanks in transit

Secure pallets

Rail cars

HGV road transport

Tunnels

Air ducts

Nuclear waste handling and storage facilities

Telecommunications—infrastructure protection

Water supplies

-   -   Remote access pumping stations    -   Critical control centers for dams    -   Manholes or access hatches    -   Chlorine stores

NBC

-   -   Pathology labs, in particular, category Four labs

Rail (including subway tunnels)

-   -   Key switching centers    -   Control rooms    -   Theft avoidance during and after construction—safety concerns        with theft of cabling

Gas and oil processing facilities

-   -   Remote facilities, particularly ship to shore interface for LNG    -   Pipelines in vulnerable areas and from ship to shore    -   Control rooms

Electricity distribution infrastructure

-   -   Sub stations' access    -   Key remote switching centers

Quarries

-   -   Remotely located explosive stores

Having thus described several features of at least one embodiment of thepresent invention, it is to be appreciated that various alterations,modifications, and improvements will readily occur to those skilled inthe art. Such alterations, modifications, and improvements are intendedto be part of this disclosure and are intended to be within the scope ofthe invention. Accordingly, the foregoing description and drawings areby way of example only, and the scope of the invention should bedetermined from proper construction of the appended claims, and theirequivalents.

1. A system for detecting a status of a container, comprising: a firstcontainment layer coupled to a surface of the container and comprising afirst sensor having a first signal path extending across substantiallyan entire area of the first containment layer; and a second containmentlayer coupled to the first containment layer and comprising a secondsensor having a second signal path extending across substantially anentire area of the second containment layer, wherein a failure of eitherthe first or second signal path to conduct a respective signal greaterthan or equal to a predetermined threshold level from a respective firstend to a respective second end signifies a breach in the respectivecontainment layer, the system further comprising: a controller coupledto the first and second signal paths and configured to characterize thestatus of the container as a function of one or more of: which of thefirst and second signal paths has failed; if both signal paths havefailed, which signal path failed first; and if both signal paths havefailed, a time period between the failures.
 2. The system of claim 1,wherein at least one of the first and second signal paths comprises oneof an optical fiber and an electrical wire.
 3. The system of claim 1,wherein at least one of the first and second containment layerscomprises a self-sealing material.
 4. The system of claim 3, wherein theself-sealing material is chosen from a resin and a self-sealing polymer.5. The system of claim 1, wherein the controller further comprises: adetector coupled to the first and second signal paths and configured todetect a respective signal from each path and to assert an alarm ifeither detected signal is less than the predetermined threshold level.6. The system of claim 1, further comprising at least one of: a firstprotective layer positioned between the first and second containmentlayers; and a second protective layer positioned over the secondcontainment layer.
 7. The system of claim 6, wherein: at least one ofthe first and second protective layers comprises anti-ballisticmaterial.
 8. The system of claim 1, wherein the first containment layercomprises a dye.
 9. The system of claim 8, wherein the dye comprises atleast one chemical compound that reacts to a first substance in acontainer.
 10. The system of claim 8, wherein the dye comprises at leastone chemical compound that reacts to air.
 11. The system of claim 1,wherein at least one of the first and second containment layerscomprises shards of material each configured to sever the respectivesignal path when the one or more shards are disturbed.
 12. The system ofclaim 1, wherein each shard comprises at least one of metal and plastic.13. The system of claim 1, wherein at least one of the first and secondsignal paths comprises optical fiber that exhibits reduced opticaltransmissibility when exposed to radiation.
 14. The security system ofclaim 1, wherein: at least one of the first and second signal pathscomprises optical fiber that exhibits reduced optical transmissibilitywhen exposed to chemically active compounds.
 15. The security system ofclaim 1, wherein: at least one of the first and second signal pathscomprises optical fiber that exhibits reduced optical transmissibilitywhen exposed to a pathogen.
 16. The security system of claim 1, whereinat least one of the first and second signal paths comprises an opticalfiber that exhibits reduced optical transmissibility when exposed tocorrosive agents.
 17. The security system of claim 16, wherein thecorrosive agents are gaseous or liquid.
 18. The system of claim 1,further comprising: a manganese security door fixedly coupled to thefirst containment layer.
 19. The security system of claim 1, wherein thecontainer comprises a manhole cover.
 20. The system of claim 1, whereinthe container comprises an access port and wherein a failure of at leastone of the first and second signal paths to conduct a signal greaterthan or equal to a predetermined threshold level from a first end to asecond end signifies a breach or an attempted breach of the containerthrough the access port.
 21. The system of claim 20, wherein the accessport is one of a hatch and a hatch cover.
 22. The system of claim 1,wherein at least one of the first and second containment layerscomprises a resin.
 23. The system of claim 1, wherein each of the firstand second containment layers is flexible.
 24. The system of claim 23,wherein at least one of the first and second containment layerscomprises an adhesive on an exposed surface.
 25. The system of claim 1,wherein the controller comprises: a signal source coupled to arespective first end of each of the first and second signal paths. 26.The system of claim 25, wherein the signal source comprises one of: anoptical signal source configured to provide an optical signal; and anelectrical signal source configured to provide an electrical signal. 27.The system of claim 26, wherein the comprises at least one of: anoptical signal detector configured to detect an optical signal; and anelectrical signal detector configured to detect an electrical signal.28. A system for detecting a status of a container, comprising: a firstcontainment layer coupled to a surface of the container and comprisingfirst and second signal paths extending across substantially an entirearea of the first containment layer, wherein each of the first andsecond signal paths is disposed in a first and second plane,respectively, the first plane being positioned between the surface ofthe container and the second plane, and wherein a failure of either thefirst or second signal path to conduct a respective signal greater thanor equal to a predetermined threshold level from a respective first endto a respective second end signifies a breach in the first containmentlayer, the system further comprising: a controller coupled to the firstand second signal paths and configured to characterize the status of thecontainer as a function of one or more of: which of the first and secondsignal paths has failed; if both signal paths have failed, which signalpath failed first; and if both signal paths have failed, a time periodbetween the failures.